Rickettsial Diseases


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  • Ehrlichiosis is a broad term used for a group of diseases that are usually named according to the host species and the type of white blood cell infected. The organisms that cause ehrlichiosis are small pleomorphic gram-negative obligate intracellular coccobacilli. There are three intracytoplasmic forms: initial body, elementary body, morula (a vacuole-bound cluster of organisms that appears as a basophilic inclusion in monocytes or granulocytes). In blood smears, the morula is diagnostic for ehrlichiosis.[Photo: Morulae detected in a monocyte on a peripheral blood smear, associated with E. chaffeensis infection. Source: CDC]
  • The onset of ehrlichiosis generally occurs about 5-10 days after a tick bite. The bacteria that causes Ehrlichiosis infects leukocytes, and more specifically, E. chaffeensis prefers to infect monocytes while E. ewingii prefers to infect granulocytes. The bacteria multiply in these cells in cytoplasmic membrane-bound vacuoles called morulae, which can sometimes be identified on blood smears. The picture to the right is an example of morulae in a monoctye caused by E. chaffeensis. A rash is observed in about 33% of patients with HME. The rash varies from a petechial or maculopapular rash to diffuse erythema and generally occurs later in the disease process. A rash is rarely seen in patients with E. ewingii infections.
  • The initial diagnosis is usually based on the history, clinical signs, hematologic abnormalities and changes in serum chemistry. Serology is used for confirmation. Human monocytic or granulocytic ehrlichiosis is usually diagnosed with an indirect immunofluorescence assay (IFA). ELISAs are also in development. The serologic tests for Sennetsu fever include an IFA and complement fixation. Cross-reactions can occur. Morulae can occasionally be found in neutrophils or mononuclear cells. Only a small percentage of cells are infected. Polymerase chain reaction testing can also detect ehrlichiae. Immunohistochemistry and in situ hybridization have been described on spleen and lymph node samples. Culture of the organism is difficult and time-consuming, and may not be practical in clinical cases. Anaplasma phagocytophilum and E. chaffeensis have been isolated from the blood of acutely ill patients, using various cell lines such as canine DH82 and human HL-60 cells. E. chaffeensis is usually found after 7 to 36 days, and A. phagocytophilum in 7 to 12 days. Species can be identified by the sequencing and analysis of 16S rRNA.[Photos: Photomicrographs of human white blood cells infected with the agent of human granulocytic ehrlichiosis (not specified) and the agent of human monocytic ehrlichiosis (Ehrlichia chaffeensis). Source: CDC Public Health Image Library]
  • Ehrlichiosis in humans is usually treated with tetracyclines; doxycycline is currently the drug of choice. Other antibiotics may be used in some circumstances. Early treatment is critical; uncomplicated cases usually respond promptly, but prolonged treatment may be necessary for severe or complicated disease.
  • The risk of infection can be decreased by preventing tick bites. Protective footwear, clothing and insect repellents should be used in tick habitats. Ticks may be more visible on light-colored clothing. People who enter tick habitats should check frequently for ticks and remove them as soon as possible, using fine-tipped tweezers or gloved hands. Bare hands should not be used to remove ticks, due to the risk of exposure to the tick’s fluids or feces; various tick-transmitted disease organisms can enter the body through cuts in the skin or mucous membranes. If gloves are not available, the fingers should be shielded with a tissue or paper towel. The tick should not be squeezed, crushed or punctured. The CDC warns that tick removal techniques such as the use of hot matches or petroleum jelly may stimulate the tick to release additional saliva and increase the risk of infection. Tick bites should be thoroughly disinfected after removal of the tick, and the hands should be washed with soap and water. The tick can be frozen in a plastic bag, for identification in case of illness. Ticks should also be removed from pets, both to prevent dogs from becoming ill and to prevent ticks from entering the home. Acaricides, biological controls and control of tick habitats can decrease the populations of tick vectors in a community. There is no vaccine for ehrlichiosis.[Images: Proper tick removal. Source: Centers for Disease Control and Prevention]
  • Rickettsial Diseases

    1. 1. Do not confuse with Rickets Vitamin D or calcium deficiency that leads to soft bones
    2. 2. Zinsser, Lice And History • In 1935, Harvard Medical School physician and researcher Hans Zinsser traced the effects of vermin-borne disease on armies, cities and populations. From his extensive research on head and body lice, Zinsser stated unequivocally that "the body and head louse carry the infection [typhus] from one human to another
    3. 3. HISTORY • 17th-19th century – Epidemics in Europe as a result of war, disaster, or in prisoners • 1909: Transmission by lice • 1917-1925: Russia – Estimated 25 million cases • End of WWII – DDT used for control – Vaccine developed
    4. 4. INTRODUCTION: • Gram -ve, non-spore forming, nonmotile, small obligate I/C highly pleomorphic bacteria • Have cell wall- Bigger than virus but smaller than bacteria • Have DNA and RNA • Have an ATP transport system that allows them to use host ATP, so replication within the cytoplasm of eukaryotic host cells • Arthropod reservoirs and vectors ( e.g., ticks, mites, lice or fleas) • Sensitive to antibiotics Center for Food Security and Public Health, Iowa State University, 2013
    5. 5. Properties:  Parasites on - Lice, Fleas, Ticks Mites colonizes the Gut In vertebrates colonizes Vascular endothelium and RES  Unstable when separated from host components. Except - R. prowazekii & R. typhi- Able to survive within louse feces for several weeks  Possess all enzymes of the TCA cycle  Glutamate- Main source of energy  Weil-Felix test- Based on the antigenic cross reactions among rickettsial antigens, mostly LPS, and Proteus vulgaris strains OX19 and OX2, and Proteus mirabilis OXK . RICKETTSIA INSIDE THE ENDOTHELIAL CELLS
    6. 6. Structure of Bacteria Similar with Gram negative bacteria Cell wall: outer membrane peptidoglycan lipopolysaccharide (LPS) Microcapsule and polysaccharide Two antigenically distinct groups: LPS: heat-stable, cross-reactive with somatic antigens of non-motile Proteus species (Weil-Felix test) Outer membrane protein: heatunstable, species-specific
    7. 7. Five genera in this class cause human diseases: Rickettsia Ehrlichia Orientia Bartonella (NOT I/C organism) Coxiella (does NOT cause skin rash & does NOT need arthropod vector) Removed from group
    8. 8. Life Cycle of Rickettsia
    9. 9. Pathogenesis: Obligate I/C organisms Dermal target cells (fibroblasts, macrophages, dermal dendritic cells, and lymphatic endothelium) Engulfed by mononuclear phagocytes in the blood stream Lungs and brain - lethality of rickettsioses ## Rickettsia rickettsii is the only organism in the genus that invades beyond the blood vessel lining endothelium; they invade adjacent vascular smooth muscle cells, particularly in arterioles
    10. 10. RICKETTSIAL INFECTIONS Classified into groups: 1 Typhus Group 2 Spotted Fever Group 3 Scrub typhus
    11. 11. Two main groups: The spotted fever group (SFG)  Mainly associated with ticks, but also with fleas (Rickettsia felis) and mites (R. akari) Typhus group (TG)  Associated with human body lice (R. prowazekii) or fleas (R. typhi)  Optimal growth temp. : 35 C  Optimal growth temp.: 32 C  G -C content (%): 32-33  Polymerize actin- Move into the nuclei of host cells - Cause spotted fevers in humans  Transovarial and transstadial transmissions are essential  G-C content (%): 29  Can’t polymerize actin- Found in the cytoplasm of host cells  Not transmitted transovarially- Have mammal reservoirs (humans for R. prowazekii, rodents for R. typhi, and cats for R. felis)
    12. 12. Typhus fever DISEASE Epidemic typhus/ SPECIES R. prowazekii VECTOR RESERVOIR(S) GEOGRAPHIC DISTRIBUTION Humans, flying Africa, Asia, North flying squirrel Sylvatic typhus Human body louse squirrels and South America Rodents Tropical and Ectoparasites Amblyomma ticks Murine typhus R. typhi Flea subtropical areas worldwide
    13. 13. EPIDEMIC TYPHUS(LOUSE BORNE TYPHUS)Rickettsia prowazekii ( Von Prowazekii ) • Humans natural vertebrate hosts • Vector - Human body louse (Pediculus humanus corporis ) Human Louse Louse Human • Severe systemic infection & prostration • If untreated, the mortality: 20-40% Russia, Eastern Europe, Devastating Epidemics in wars • Napoleons retreat • Russia 3 million deaths 1917 – 1921 • Major killer in concentration camps of WW II • Brill-Zinsser Disease  recrudescent disease LIFE CYCLE
    14. 14. • Human body louse – Pediculus humanus corporis – Infective for 2-3 days – Infection acquired by feeding on infected person – Excrete R. prowazekii in feces at time of feeding – Lice die within 2 weeks • Louse feces rubbed into bite or superficial abrasions • Inhalation of feces • Sylvatic typhus – Flying squirrel – 30 human cases in eastern and central U.S.
    15. 15. Vasculitis Skin – rashes, DIC & vascular occlusion Swollen & necrotic Thrombosis of the vessels Clinical Symptoms Multiply in endothelial cells of small blood vessels Incubation: 7-14 days High fever, chills, headache, cough, myalgia May lead to coma Macular eruption 5-6 days after onset Initially on upper trunk, spreads to entire body Except face, palms and soles of feet
    16. 16. Endemic Typhus • Murine or Flea borne typhus • Mild disease • Rat act as reservoir Flea Rodent Rodent Flea • Vector : Rat flea-Xenopsylla cheopsis • Man gets infected accidentally • Saliva or feces rubbed on bitten area, may lead to infection • R.typhi & R. Prowazekii similar, Biological & Immunological tests
    17. 17. Neill-Mooser Reaction • Male guinea pig inoculated intra peritioneally with blood of patients – Fever, scrotal swelling • Enlarged tests, and cannot be pushed back.-due inflammation and adhesions between layers of Tunica vagina • Test positive for R.typhi and negative for R. prowazekii
    18. 18. Spotted fever................ DISEASE Rickettsiosis SPECIES VECTOR R. aeschlimannii Tick RESERVOIR(S) Unknown GEOGRAPHIC DISTRIBUTION South Africa, Morocco, Mediterranean littoral African tick-bite R. africae Tick Ruminants Sub-Saharan Africa, West Indies R. akari Mite House mice, wild Countries of the former Soviet rodents Union, S. Africa, Korea, Turkey,, fever Rickettsialpox North and S. America Queensland tick R. australis Tick Rodents Australia, Tasmania R. conorii Tick Dogs, rodents Southern Europe, southern and typhus Mediterranean spotted fever / western Asia, Africa, India Boutonneuse fever Cat flea rickettsiosis R. felis Flea Domestic cats, Europe, North and South rodents, opossums America, Africa, Asia Cont.........
    19. 19. Spotted fever................ DISEASE Mediterranean spotted SPECIES R. massiliae VECTOR RESERVOIR(S) Tick Unknown fever-like disease GEOGRAPHIC DISTRIBUTION France, Greece, Spain, Portugal, Switzerland, central Africa, and Mali Mediterranean spotted R. monacensis Tick fever-like illness Lizards, possibly Europe, North Africa birds Maculatum infection R. parkeri Tick Rodents North and South America Tickborne R. raoultii Tick Unknown Europe, Asia R. rickettsii Tick Rodents North, Central, and South lymphadenopathy/ Dermcentor-borne necrosis Rocky Mountain spotted fever/ febre maculosa/ America Brazilian spotted fever Cont.........
    20. 20. Spotted fever................ DISEASE Flinders Island spotted fever/ Thai SPECIES R. honei VECTOR RESERVOIR(S) Tick tick typhus Rodents, GEOGRAPHIC DISTRIBUTION Australia, Thailand reptiles Japanese spotted fever R. japonica Tick Rodents Japan North Asian tick typhus/ Siberian R. sibirica Tick Rodents Russia, China, tick typhus Tickborne lymphadenopathy (TIBOLA)/ Dermacentor-borne necrosis and lymphadenopathy (DEBONEL) Mongolia R. slovaca Tick Lagomorph Southern and s, rodents eastern Europe, Asia
    21. 21. Rocky mountain spotted fever Rickettsia rickettsii Ticks acts as vectors & reservoirs of Infection
    22. 22. Scrub typhus DISEASE SPECIES VECTOR Scrub typhus Orientia tsutsugamushi Larval mite (chigger) Scrub typhus Orientia chuto Unknown RESERVOIR(S) GEOGRAPHIC DISTRIBUTION Rodents Asia-Pacific region from maritime Russia and China to Indonesia and North Australia to Afghanistan Unknown Dubai
    23. 23. Scrub typhus Etiology: Orientia tsutsugamushi • Resembles Epidemic typhus except for the ESCHAR • Generalized lymphadenopathy & lymphocytosis •Cardiac & cerebral involvement may be severe Epidemiology Source of infection--Rat Route of transmission--Trombiculid mites Eschar Probability: Higher than 60% Location: Axillary fossa, inguinal region, perianal region, scrotum, buttocks and the thigh Appearance: an ulcer surrounded by a red areola, is often covered by a dark scab Susceptible population--All susceptible Epidemic features-Tsutsugamushi triangle
    24. 24. Scrub Typhus Important vector-borne disease, first described in 1899 in Japan. During World War II, this disease killed thousands of soldiers who were stationed in rural or jungle areas of the Pacific theatre The disease occurred and threatened people throughout Asia & Australia. The range stretches from the Far-east to the Middle-east (from Japan and Korea, Southeast Asia, Pakistan, India, to Arab countries and Turkey). There are approx. 1 million cases each year world-wide, & over 1 billion people at risk
    25. 25. Scrub Typhus: A Rickettsial Disease Pathogen: Orientia tsutsugamushi Rickettsial bacteria Vector: Leptotrombidium An acute febrile, rickettsial disease caused by a gram-negative, rodshaped (cocco-bacillus) bacterium, known as Orientia (Rickettsia) tsutsugamushi. Chigger-Mite O. tsutsugamushi is transmitted to vertebrate hosts (rodents-primary host & humanssecondary or accidental host) by the bite of larval mites (chiggers) of the genus Leptotrombidium, e. g. L. deliense, L. dimphalum, etc.
    26. 26. Pathogenesis Inoculation Papule maculoppular Eschar ulcer Invade Local lymph node Enlargement of local LN Spread by Blood stream General symptoms of intoxication Invade Vascular endothelium Organ hyperaemia Systemic lyphadenopathy
    27. 27. Miscellaneous............ GROUP Anaplasma DISEASE SPECIES VECTOR RESERVOIR(S) GEOGRAPHIC DISTRIBUTION Tick Small mammals, rodents, and deer Primarily United States, worldwide Tick Ehrlichosis E. muris Tick Deer, dogs, ruminants, and rodents Deer and rodents Ehrlichosis Ehrlichia Human granulocytic A. phagocytoanaplasphilum mosis Human monocytic E. chaffeensis ehrlichosis E. ewingii Tick N. mikurensis Tick Common in United States, probably worldwide North America, Europe, Asia North America, Cameroon, Korea Europe, Asia N. sennetsu Trema- Fish tode Neoehrlichia Human neoehrlichiosis NeorickSennetsu fever ettsia Deer, dogs, and rodents Rodents Japan, Malaysia, possibly other parts of Asia
    28. 28. Human monocytic ehrlichiosis • Causative agents: – Ehrlichia chaffeensis – Ehrlichia ewingii – Ehrlichia muris • Primary vector- Lone star tick (Amblyomma americanum) • Symptoms – – Fever, headache, malaise, and myalgia Rash is more common • Diagnosis: • Laboratory abnormalities – Thrombocytopenia, leukopenia, and elevated liver tests • PCR - laboratory diagnostic tool of choice • Treatment: – Doxycycline is the treatment of choice.
    29. 29. Clinical Information • Onset: 5–10 days after tick bite • Infects leukocytes – E. chaffeensis prefers monoctyes – E. ewingii prefers granuloctyes – Morulae can be identified • Rash observed ~33% of patients • Rash rarely seen with E. ewingii infections Diagnosis: •Confirmed –Fourfold change in IgG by IFA in paired serum samples –Detection of DNA by PCR –Isolation of bacteria by cell culture •Supportive –Elevated IgG or IgM by IFA, ELISA, dot-ELISA or other formats –Morulae identification by blood smear microscopic examination
    30. 30. Why they seek attention??? Economic losses to livestock industries Financial costs to owners - Veterinary treatments -Tick-prevention programs Animal Rickettsioses Mental and emotional distress to the owners.
    31. 31. Common slayers for animal population ...... Species Disease Vector Animal Distribution Anaplasma bovis NOFEL Amblyomma spp., Hyalomma spp., Rhipicephalus spp. Cattle S. America, Africa, Iran, India A. marginale Bovine anaplasmosis/gallsickness Various ticks Biting insects Cattle Worldwide A. ondiri Bovine petechial fever /Ondiri disease Unknown Cattle Africa A. ovis Ovine/caprine anaplasmosis Various ticks Sheep, goats Worldwide Ixodes spp. Horses America, Europe A. phagocytophilum Equine ehrlichiosis Canine granulocytic ehrlichiosis/anaplasmosis Dogs Feline granulocytic ehrlichiosis/anaplasmosis Cats Pasture fever/ tick-borne fever Ruminants
    32. 32. List is not meant to be exhaustive........... Species Disease Vector Animal Distribution Ehrlichia canis Canine monocytic ehrlichiosis Rhipicephalus sanguineus Dogs Worldwide E. chaffeensis Canine monocytic ehrlichiosis Amblyomma americanum Dogs N. America E. ewingiia Canine granulocytic A. americanum ehrlichiosis Dogs N. America, Africa E. ruminantium Heartwater Amblyomma spp. Cattle, sheep, goats Africa, Caribbean N. risticii Potomac horse fever/ Equine monocytic Neorickettsiosis Digenic trematodes Horses N. America
    33. 33. BOVINE ANAPLASMOSIS/GALLSICKNESS • Cuasative organisms: • A. marginale - Clinical outbreaks • A. centrale - limited pathogenicity • Anaplasma phagocytophilum - Zoonotic • Prevalence- All six continents, especially in tropical areas TRANSMISSION: Physical Vectors • Flies • Horse Flies • Stable Flies • Dear Flies • Mosquitoes • Instruments • Surgical Instrumants • Dehorning Instruments • Castration Instruments • Hypodermic Needles Biological Vector • Ticks
    34. 34. PATHOGENESIS RBCs lysis -Anemia -Lack of O2 & Nutrients in Tissue Calves Under • Show no Signs or Symptoms 6 Moths Animal remains carrier Up to 18 months old Mature Cattle • Show only Symptoms • Show Signs & Symptoms
    35. 35. Heartwater Cowdriosis, Malkopsiekte, Pericardite Exsudative Infectieuse, Hidrocarditis Infecciosa, Idropericardite Dei Ruminanti Causative agent: Ehrlichia ruminantium Geographic Distribution: Sub-Saharan Africa The Caribbean Islands Not reported in Asia Tick introduction into U.S. possible Animal Transmission •Vector-borne - Amblyomma ticks •Larvae and nymphs infected from infected animals
    36. 36. Clinical Signs • Incubation period: 14 to 28 days • Four forms of disease – Peracute (rare) – Acute (most common) – Subacute (rare) – Mild or subclinical Acute form: •Most common form •Sudden fever (107oF) •Inappetence, depression •Tachypnea, respiratory distress •Nervous signs Chewing movements, eyelid twitching, tongue protrusion, circling, paddling •Death in 1 week Hydropericardium Post Mortem Lesions • • • • Hydropericardium Hydrothorax Ascites Pulmonary & mediastinal edema • Congestion and edema in the brain Hydrothorax Cytoplasm of capillary endothelial cells of infected animals
    37. 37. Diagnosis: Clinical signs Fever, respiratory distress, sudden death Presence of Amblyomma ticks Laboratory Tests Microscopic identification organism PCR, IFA, ELISA Treatment • Early stage – Oxytetracycline • Late stage – When neurological signs occur – Usually futile Vaccination: Attenuated E. ruminantium BALL3-strain serial passage confers solid immunity
    38. 38. NOFEL • NOFEL (ear in local language) can be seen in monocytes of cattle from S. America, Africa, and the Indian subcontinent • Causative agent: Anaplasma bovis • Vector: – Multiple ticks (Amblyomma, Hyalomma, and Rhipicephalus) • The disease is particularly severe in cattle stressed by rain, emaciation, or high tick burdens
    39. 39. Characterized by: – – – – – fever depression lymph node enlargement nasal and ocular discharge severe lung edema, and renal necrosis  Animals frequently shake their heads and one or both ears are held downward over the parotid salivary gland which is markedly inflamed, swollen, and painful Treatment: Tetracyclines
    40. 40. BOVINE PETECHIAL FEVER/ONDIRI DISEASE • Etiological agent- Anaplasma ondiri – Occurs mainly in neutrophils • Clinical signs: – High fever – Hemorrhagic diathesis over 10 days – Anemia, severe leucopenia and thrombocytopenia – Sudden agalactia and may abort • Diagnosis : – organisms in blood smears Treatment: – Tetracyclines are effective – Cattle surviving infections become carriers for many months or years POSTMORTEM LEISONS
    41. 41. TICK BORNE FEVER/ PASTURE FEVER Anaplasma phagocytophilum  Tickborne fever (TBF) is a febrile disease of domestic and free-living ruminants in the temperate regions Transmitted by hard tick-Ixodes ricinus Main hostsSheep and cattle, goats and deer are also susceptible
    42. 42. CATTLE • Known as Pasture fever • Dullness & depression, with a marked loss of appetite and milk yield • Respiratory distress & coughing SHEEP Main clinical sign is a sudden fever 40.5- 42.0 C for 4-10 days  Other signs are either absent or mild, animals appear dull & may lose weight Abortions in susceptible ewes & cows, newly introduced onto tickinfested pastures Quality of the semen of infected rams and bulls may be greatly reduced
    43. 43. Diagnosis • Case history: Young animals born in tickinfested areas or in older animals newly introduced to such area Treatment  Short-acting oxytetracyclines Most effective treatment Sulfamethazine also proved useful • Hematologic changes • Presence of inclusions within granulocytes  Organism infects eosinophils, neutrophils, & monocytes, in that order  Cytoplasmic inclusions- Grayish blue bodies in Giemsa-stained blood smears
    44. 44. Canine Monocytic Ehrlichiosis Tracker dog disease Canine haemorrhagic fever Tropical canine pancytopaenia The Brown Dog Tick (Rhipicephalus sanguineus) Ehrlichia canis - usually spreads Ehrlichia canis, Ehrlichia ewingii, and other diseases.
    45. 45. Clinical signs • Nonspecific signs – -Fever, Anorexia & lethargy -Lymphadenopathy, spleenomegaly & weight loss Ocular signs: Anterior uveitis, corneal opacity, hyphema and tortuous retinal vessels • Vomiting, diarrhea, lameness, edema in the hindlegs, dyspnea, & purulent oculonasal discharge Corneal opacity • Bleeding disorders - Anemia, mild epistaxis, petechiae and ecchymoses • Death - Consequence of hemorrhages or secondary infections
    46. 46. Diagnosis POSTMORTEM LEISONS • A dog with fever, enlarged lymph nodes, bleeding, or arthritis in multiple joints. • Low platelet numbers, high globulin levels, and mild anemia on blood testing Canine thrombocytopaenia Pancytopenia Ehrlichia canis seen in a membrane-bound inclusions (morulae) within the cytoplasm of a monocyte (buffy coat smear, Wright stain)
    47. 47. TREATMENT  Doxycycline - 10mg/kg once daily for a period of three weeks at least- Treatment of choice for acute CME  Imidocarb dipropionate - 5mg/kg, one or two injections at 14 day interval, IM
    48. 48. Canine Granulocytic Ehrlichiosis (Ehrlichia ewingii)  Disease of neutrophils  CGE classically presents with mild signs  fever, lethargy, anorexia, weight loss, vomiting, diarrhea, severe but transient thrombocytopenia, and transient mild nonregenerative anemia with ineffective erythropoeisis  Major clinical signs –  lameness and joint swelling due to polyarthritis Neutrophil containing morula of Ehrlichia ewingii (blood smear, Wright stain)
    49. 49. Potomac horse fever /Equine monocytic ehrlichiosis • Causative agent: Neorickettsia risticii – Also known as Shasta River Crud and Equine Monocytic Ehrlichiosis – It was first described in areas surrounding the Potomac River of Washington, D.C., in the 1980s • Transmission: – Freshwater snails and aquatic insects, such as caddisflies, mayflies, damselflies, dragonflies, and stoneflies is a reservoir for N. risticii  Clinical signs: - Depression - Loss of appetite - Fever, followed by diarrhea
    50. 50.  Pathogenesis: Organism multiplies inside the intestinal tractColitis Bacterial toxins gain access to the blood stream Laminitis, even collapse of the circulation, abortion in pregnant mares and death Treatment: •Responds well to tetracycline • Mild cases - oral doxycycline •Severe cases - i/v oxytetracycline
    51. 51. EQUINE EHRLICHIOSIS/EQUINE GRANULOCYTIC ANAPLASMOSIS • Etiological agent: A. phagocytophilum • Epidemiology: – Common in California but has been reported across the U.S, Europe & S. America • Vectors: Ixodes spp. • Clinical signs: • Most infections are subclinical • In severe vasculitis, clinical signs evolve: – – – – – Fluctuating fever Depression Partial anorexia Ataxia, reluctance to move & limb edema icterus
    52. 52. • Diagnosis: • Laboratory abnormalities – anemia, – leucopenia, – thrombocytopenia, and increased bilirubin • Morulae are readily seen in neutrophils or eosinophils • Can also be diagnosed using an IFA or using PCR • Treatment: • Oxytetracycline (7 mg/kg IV q24 hours) • There is no vaccine, and infections are best prevented by tick control
    53. 53. INDIAN SCENERIO: A GLIMPSE Has been reported from 11 states in India: Re-emerging High magnitude of scrub typhus, spotted fever and Indian tick typhus (Batra HV, 2007) Jammu and Kashmir Himachal Pradesh Uttaranchal Rajasthan Assam West Bengal Maharashtra Pondichery Kerala Tamilnadu (Mahajan S. K, 2012) Many cases go undiagnosed ??? •Lack of diagnostic tools • Less clinical awareness • Lower index of suspicion
    54. 54. Diagnosis: Staining: Not stained by the Gram’s method Retain basic fuschin when stained with Gimenez methodBright red • Initial diagnosis – History, clinical signs – Hematologic abnormalities – Serum chemistry • Definitive diagnosis – IFA – ELISA – PCR – Culture Clinical Signs Blood Smears Serological Biopsy Center for Food Security and Public Tests Health, Iowa State University, 2013 Gene Diagnosis
    55. 55. Diagnosis and Prevention Microscopy Serological Test Breaking the infection chain  Controlling/killing the I/H or reservoir hosts Inactivated vaccines Drug therapy  Sulphonamides are not administered-Increasing the penetrating of the vessel 57
    56. 56. Different Methods of Diagnosis Tissue cultures In Vero cells MRC – 5 cells
    57. 57. Older Techniques 1. Giemsa Staining Technique :- utilizes peritoneal scrapings of infected mice. 2. Weil-Felix Proteus Agglutination Test :-Relies on the fact that Rickettsia and Proteus OX strains have common antigens :-Test for the presence & type of rickettsial disease based on the agglutination of X-strain Proteus vulgaris with suspected Rickettsia in a patient’s blood serum sample :-Commonly used in hospitals & clinics :-This test is now being replaced by a complement-fixation test. Weil-Felix Proteus Agglutination Test
    58. 58. Serology Weil – Felix Test Based on principle of Hetrophile agglutination tests • Non motile strains of Proteus are selected DISEASE WEIL-FELIX OX1 OX OX 9 2 K Epidemic typhus ++ +/- - • OX19,OX2,OXK Endemic typhus ++ - - • Sharing alkali stable carbohydrate antigen by some Rickettsia and certain strains of Proteus vulgaris OX19,OX2, and P. mirabilis OXK Scrub typhus - - ++ RMSF + + - Rickettsial pox - - - Q fever - - -
    59. 59. Newer Techniques Immunological Assays 2. Indirect Immuno-Peroxidase (IIP) IIP= is a modification of IFA technique that replaces the fluorochrome with peroxidase Slide is observed using a bright-field microscope Staining reaction is + ve when O. tsutsugamushi particles stain light brown. Control Infected
    60. 60. Newer Techniques Immunological Assays 4. Enzyme-linked Immuno-Sorbant Assay (ELISA) ELISA test is a technique for detecting & measuring antigen or antibody :- One of the most reliable techniques to detect antibody against scrub typhus infection :- Its procedure is the principal for development of recent rapid diagnostic kits. Widely used in laboratories & hospitals. Ag-Ab complex Optical Density (OD) Reading Ag-coated well 1. Add antigens 2. Add mouse serum 3. Add anti-Ab 4. Add enzymesubstrate mix 5.Let colorize
    61. 61. Treatment: • Antibiotics – Tetracyclines • Doxycycline – Early treatment critical – Prolonged therapy- In severe or complicated cases ## Rickettsial growth is enhanced in the presence of sulfonamides Center for Food Security and Public Health, Iowa State University, 2013
    62. 62. What we can do????? Queensland tick typhus Human monocytic ehrlichosis Japanese spotted fever Murine typhus North Asian tick typhus/ Siberian tick typhus Maculatum infection Scrub typhus Human granulocytic anaplasmosis Rickettsialpox TIBOLA/ DEBONEL Mediterranean spotted fever Human neoehrlichiosis Flinders Island spotted fever Rocky Mountain spotted fever
    63. 63. Prevention and Control • Prevent tick bites – Wear protective clothing – Use insect repellents – Remove ticks as soon as possible • Control tick vectors •Remove ticks from pets • Acaricides • Pets, livestock, environment •Biological controls •Chemotherapy • Immunity Center for Food Security and Public Health, Iowa State University, 2013